1. Field of the Invention
The invention generally relates to an apparatus and method for exotic cadence detection, and more particularly to a film mode detection method and system that is programmable for a plurality of cadences including conventional and exotic cadences in TV and Set-Top-Box products.
2. Discussion of the Related Art
Modern video displays, e.g., liquid crystal displays (LCD) and plasma displays, are not able to operate in an interlaced mode. Interlace is found throughout a number of broadcasting formats. Therefore de-interlacing circuitry is needed in set-to-box (STB)/TV to de-interlace video into progressive video that can be played on modern video displays.
Currently, there are a number of different source formats, e.g., video camera may be captured at 50 or 60 frames per second, film format may be captured at 24 or 25 frames per second, and various animations may be smaller, e.g., 8 frames per second. There are also a variety of different display formats, e.g., phase alternating line (PAL), primarily used in Europe, displays 50 fields per second, the national television standards committee, (NTSC) format, and various other formats.
Cadence detection is required and permits one to find the source format of a sequence of video fields, or detect the absence of motion between frames (still pictures). Typically, when a video source is a Telecine source, i.e., originally progressive film-source, inverse Telecine can recover the video, without picture quality degradation induced by a de-interlacer.
As known in the art, cadence detection is based on comparisons of pixels belonging to successive fields of index n and performed in order to determine the existence of motion between one frame and another. A conversion typically leads to abrupt motion as described with reference to U.S. Patent Application Publication No. 2007/0296858. U.S. Patent Application Publication No. 2007/0296858 also describes conventional and exotic cadence detection based on searching for a cadence pattern in a sequence of bits representative of inter-field motion and also accounting for field skip and/or repeat situations.
The conventional cadence detectors have limited robustness. For example, the limited robustness is due many cadences to be checked including conventional (2:2 and 3:2) and exotic cadences. In addition, conventional cadence detectors have long latencies especially as the cadence length is increased, e.g., Telecine B—25 fields.
Accordingly, there is a need in the art to robustly, rapidly and efficiently provide cadence detection.